JP2006011343A - Process cartridge and electrophotographic image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent leaking of current, from a charging roller to an adjacent electroconductive member. <P>SOLUTION: This process cartridge has a thin-plate elastic sheet 71, brought into a sliding contact with the periphery surface of the charging roller 2 and the sheet exists between the electroconductive member 59a and the charging roller 2, with the length of the elastic sheet 71 being made longer than that of the contact region of the charging roller 2 that contacts with an electrophotographic photoreceptor drum. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic image forming apparatus and a process cartridge used therefor.

  Conventionally, in an electrophotographic image forming apparatus using an electrophotographic image forming process, the electrophotographic photosensitive drum and the process means acting on the photosensitive drum are integrated into a cartridge, and the cartridge can be attached to and detached from the image forming apparatus. The process cartridge method is adopted. According to this process cartridge system, maintenance of the apparatus can be performed by the user himself. Therefore, the operability can be remarkably improved. Therefore, this process cartridge system is widely used in electrophotographic image forming apparatuses.

  As a method of charging a photosensitive drum in a process cartridge, a method of rotating a charging roller as a charging member following a photosensitive drum is generally known.

  Even after development and after cleaning with a cleaning member, a very small amount of developer or a charge control material contained in the developer may be present on the photosensitive drum as an adhering substance. In such a case, the deposit adheres to the charging roller, and the surface of the charging roller is gradually soiled. And charging performance falls. As a method for preventing such contamination of the charging roller and improving durability, a method of providing a rubbing member on the charging roller has been devised (see Patent Document 1 and Patent Document 2).

  On the other hand, in the electrophotographic image forming apparatus, a high voltage is applied to the charging roller. Therefore, the charging roller and the conductive member are assembled at a predetermined distance so that the current flowing through the charging roller does not leak to other adjacent conductive members (components).

JP-A-2-272594 Japanese Patent Laid-Open No. 7-199604

  However, recent image forming apparatuses are also required to be compact. For this purpose, it is necessary to downsize the image forming apparatus main body and the process cartridge that occupies a large space in the image forming apparatus. From this point of view, it is necessary to miniaturize the parts constituting the process cartridge and to efficiently arrange the parts. That is, it is required that the distance between conductive members (components) be reduced. Therefore, when the installation interval between the charging roller and the component is made smaller than a predetermined distance, there is a concern that current leaks from the charging roller to which a high voltage is applied to another adjacent component. When current leakage occurs, a high-quality image cannot be obtained. Therefore, conventionally, the installation interval between the charging roller and the conductive member (component) has been increased by a predetermined distance or more.

  An object of the present invention is to provide a process cartridge capable of making an installation distance between a charging member and a conductive member smaller than a conventional installation distance, and an electrophotographic image forming apparatus using the process cartridge.

  Another object of the present invention is to provide a process cartridge capable of preventing current from leaking from the charging member to the conductive member when a charging bias is supplied to the charging member, and an electronic device using the process cartridge. A photographic image forming apparatus is provided.

  Another object of the present invention is to provide a process cartridge that is downsized and an electrophotographic image forming apparatus using the process cartridge.

  Another object of the present invention is to increase the length of the charging member rubbing member to be longer than the length of the contact area where the charging member is in contact with the electrophotographic photosensitive drum. An object of the present invention is to provide a process cartridge capable of preventing a current from leaking from a charging member to a conductive member in addition to a function of rubbing the surface, and an electronic image forming apparatus using the process cartridge.

  Another object of the present invention is to generate a leak even in a use environment (for example, when the humidity is high) in which there is a risk of a leak occurring when the charging member rubbing member is not interposed. It is an object of the present invention to provide a process cartridge that does not perform and an electrophotographic image forming apparatus using the process cartridge.

  The present invention has been made in view of the above points. That is, the present invention relates to an electrophotographic photosensitive drum and a process cartridge that are detachable from an electrophotographic image forming apparatus main body. Is mounted on the electrophotographic image forming apparatus main body, is supplied with a charging bias received from the electrophotographic image forming apparatus main body to charge the electrophotographic photosensitive drum, and the charging member Insulating charging member and rubbing member provided in contact with the charging member along the longitudinal direction, and preventing leakage of current between the conductive member and the charging member In order to achieve this, the charging member rubbing member extends beyond the end in the longitudinal direction of the charging region where the charging member charges the electrophotographic photosensitive drum. Process cartridge is positioned between said charging member, and is to provide an electrophotographic image forming apparatus detachably mountable a process cartridge.

  According to the present invention, the installation distance between the charging member and the conductive member can be reduced. Therefore, the process cartridge can be reduced in size. Further, it is possible to prevent leakage of current from the charging member to the conductive member in spite of the downsizing.

  Next, a process cartridge and an electrophotographic image forming apparatus using the same according to an embodiment of the present invention will be described.

[First embodiment]
[Overall configuration of color electrophotographic image forming apparatus]
First, the overall configuration of the color electrophotographic image forming apparatus will be described with reference to FIGS. 1 and 2 are explanatory diagrams of the entire configuration of a full-color laser printer which is an embodiment of a color image forming apparatus, and FIG. 3 is an explanatory diagram of the entire configuration of a process cartridge used therefor.

  As shown in FIG. 1, the color laser printer has a process cartridge 7 having an electrophotographic photosensitive drum for each color of yellow, magenta, cyan, and black, and a color image developed by the process cartridge 7 and multiple-transferred. And an intermediate transfer member 5 that is further transferred to the recording medium P fed from the feeding unit. The electrophotographic photosensitive drum 1 (1a, 1b, 1c, 1d) is driven to rotate counterclockwise in FIG. A photosensitive roller 1 (2a, 2b, 2c, 2d), which uniformly charges the surface of the photosensitive drum 1 in order according to its rotation direction, and a laser beam are irradiated on the periphery of the photosensitive drum 1 based on image information. A scanner unit 3 (3a, 3b, 3c, 3d) for forming an electrostatic latent image on the photosensitive drum 1, and a developing device 4 for developing the electrostatic latent image by attaching a developer to the electrostatic latent image (FIG. 3). Reference) is provided. Further, after the developer on the photosensitive drum 1 is transferred to the intermediate transfer member 5 at the first transfer portion T1, the photosensitive drum unit 6 having a drum cleaning device for removing the developer remaining on the surface of the photosensitive drum 1 (FIG. 3). Reference) is provided. The developer image transferred to the intermediate transfer member 5 is further transferred to the recording medium P by the secondary transfer roller 13 at the second transfer portion T2. Then, the recording medium P is conveyed to the fixing unit 8 and the color image is fixed on the recording medium P. Then, the recording medium P is discharged to the discharge tray 26 by the discharge roller group 25.

  Here, the photosensitive drum 1 (1a to 1d), the charging roller 2 (2a to 2d), the developing device 4, and the drum cleaning device are integrally formed into a cartridge, and the process cartridge 7 (7a, 7b, 7c, 7d) is formed. It is composed. The cartridge 7 is detachably mounted on a mounting portion 80 (80a, 80b, 80c, 80d) provided in the electrophotographic image forming apparatus main body 100.

  Further, the apparatus main body 100 has an open / close cover 29 that integrally includes the intermediate transfer member 5. As shown in FIG. 2, the process cartridge 7 is attached to and detached from the image forming apparatus main body 100 with the photosensitive drum 1 facing forward with the opening / closing cover 29 opened. That is, the process cartridge 7 can be attached to and detached from the image forming apparatus main body 100.

  Next, the configuration of each part of the image forming apparatus will be sequentially described in detail with reference to FIGS. 1 and 3.

[Photosensitive drum]
Next, the electrophotographic photosensitive drum 1 will be described in detail.

  The photosensitive drum 1 is obtained by coating an organic photoconductive layer (OPC photosensitive member) on the outer peripheral surface of an aluminum cylinder having a diameter of about 20 to 50 mm, for example. Both ends of the photosensitive drum 1 are rotatably supported by support members. A driving force from a driving motor (not shown) is transmitted to one end. As a result, the photosensitive drum 1 is driven counterclockwise (FIG. 3).

[Charging member]
The charging roller 2 (2a to 2d) as the charging member uses a contact roller charging method. The charging roller 2 is a conductive roller configured in a roller shape. The roller is brought into contact with the surface of the photosensitive drum 1 and a charging bias is supplied to the roller. As a result, the surface of the photosensitive drum 1 is uniformly charged. That is, the charging member (hereinafter referred to as “charging roller”) 2 is supplied with a charging bias received from a main body power supply E provided in the apparatus main body 100 when the cartridge 7 is mounted on the apparatus main body 100. The photosensitive drum 1 is charged. In the present embodiment, the charging bias is 1000 to 1500 (V).

[Exposure means]
The scanner unit 3 which is an exposure unit has a laser diode (not shown). When the image signal is applied to the laser diode, the laser diode irradiates image light corresponding to the image signal onto the polygon mirror 9 (9a, 9b, 9c, 9d) rotated at high speed by the scanner motor. The image light reflected by the polygon mirror 9 selectively exposes the surface of the photosensitive drum 1 rotating through the imaging lens. As a result, an electrostatic latent image is formed on the photosensitive drum 1.

[Development equipment]
The developing device 4 develops the electrostatic latent image. For this purpose, a developer accommodating portion 41 that accommodates yellow, magenta, cyan, and black color developers is provided. The developer in the developer accommodating portion 41 is sent to the developer supply roller 43 by the conveying means 42. Then, the developer is attached to the outer periphery of the developing roller 40 rotated (in the arrow Y direction in FIG. 3) by the rotating rotating blade (in the clockwise direction of FIG. 3) and the developing blade 44 pressed against the outer periphery of the developing roller 40. In addition, a charge is imparted to the developer.

  A developing bias is supplied from the power source E to the developing roller 40 facing the photosensitive drum 1 on which the latent image is formed. Thereby, the latent image is developed. The developing bias in this embodiment is 300 to 800 (V).

[Intermediate transfer member]
The intermediate transfer member 5 performs multiple transfer of the developer image on the photosensitive drum 1. Therefore, it rotates in the clockwise direction of FIG. 1 in synchronization with the outer peripheral speed of the photosensitive drum 1. The developer image formed on the photosensitive drum 1 is arranged at a position opposed to the photosensitive drum 1 with the intermediate transfer member 5 interposed therebetween, and the primary transfer roller 12 (12a, 12b, 12c, 12d) to which a voltage is applied. Multiple transfer is performed on the intermediate transfer body 5 at the primary transfer portion T1 which is a contact. The intermediate transfer member 5 that has undergone multiple transfer sandwiches and conveys the recording medium P by the secondary transfer roller 13 to which a voltage is applied in the transfer portion T2. As a result, the color developer images on the intermediate transfer body 5 are simultaneously transferred onto the recording medium P in a multiple manner.

  The intermediate transfer member 5 (intermediate transfer belt) according to this embodiment is stretched around three axes of a drive roller 14, a secondary transfer counter roller 15, and a tension roller 16.

[Feeding department]
The feeding unit feeds the recording medium P to the photosensitive drum 1. The feeding unit includes a cassette 17 that stores the recording medium P, a feeding roller 18, a separation pad 19, a guide 20, and a registration roller pair 21. At the time of image formation, the feeding roller 18 is driven and rotated according to the image forming operation. Then, the recording media P in the cassette 17 are separated and fed one by one. The fed recording medium P is guided by the guide 20 and reaches the registration roller pair 21 via the conveyance roller. During the image forming operation, the registration roller pair 21 performs a non-rotating operation for causing the recording medium P to stand still and a rotating operation for conveying the recording medium P toward the intermediate transfer member 5 in a predetermined sequence. The roller pair 21 aligns the image and the recording medium P in the next transfer process.

[Transfer section]
The transfer unit has a swingable secondary transfer roller 13. The transfer roller 13 is movable in the vertical direction and rotates. In synchronization with the timing for transferring the color image to the recording medium P, the transfer roller 13 is pressed against the intermediate transfer body 5 by a cam member (not shown) via the recording medium P with a predetermined pressure. At the same time, a bias is applied to the transfer roller 13. As a result, the developer image on the intermediate transfer member 5 is transferred to the recording medium P. The recording medium P is transported by the transport belt 22 toward the fixing device 8 which is the next process.

[Fixing part]
The fixing device 8 fixes the developer image formed on the recording medium P. The fixing device 8 includes a film guide unit 23 having a built-in ceramic heater for applying heat to the recording medium P, and a pressure roller 24 for pressing the recording medium P against the film guide unit.

  With the above configuration, latent images are formed in the order of yellow, magenta, cyan, and black. Then, development and transfer of the developer image to the intermediate transfer member 5 are performed at each primary transfer position T1. Then, a full color image composed of four types of developers of yellow, magenta, cyan, and black is formed on the surface of the intermediate transfer member 5. This full-color developer image is transferred to the recording medium P. Then, after fixing, a full color image is formed on the recording medium P.

[Configuration of process cartridge]
Next, a process cartridge 7 to which an embodiment of the present invention is applied will be described with reference to FIGS. 3, 4 and 5. 3, 4 and 5 show a main cross section and a perspective view of the cartridge 7 containing the developer. The process cartridges 7a, 7b, 7c, and 7d containing the color developers of yellow, magenta, cyan, and black have the same configuration.

  As shown in FIG. 3, the process cartridge 7 develops the photosensitive drum 1, the photosensitive drum unit 6 including the charging roller 2 and the drum cleaning blade 60, and the electrostatic latent image formed on the photosensitive drum 1. A developing unit (developing device) 4 having a developing roller 40 is provided.

  In the drum unit 6, the photosensitive drum 1 is rotatably attached to the cleaning frame 61 via a bearing member 31. As shown in FIG. 3, the photosensitive drum 1 rotates counterclockwise, and adheres to the charging roller 2 as a charging member for uniformly charging the surface of the photosensitive drum 1 and the photosensitive drum 1. A drum cleaning blade 60 as a drum cleaning member for removing the developed developer is disposed. That is, the cleaning blade 60 removes deposits (developer, paper dust, etc.) adhering to the photosensitive drum 1.

  The removed developer or the like removed from the surface of the photosensitive drum 1 by the cleaning blade 60 is sent to the removed developer chamber 63 provided behind the cleaning frame 61 by the developer feeding mechanism 62.

  The developing unit 4 includes a developing roller 40, a developer storage unit 41 that stores a developer, and a developing container 45 that rotates in contact with the photosensitive drum 1 (in the arrow Y direction). The developing roller 40 is rotatably supported by the developing container 45 via developing bearings 47 and 48 (see FIG. 4). A developer supply roller 43 and a developing blade 44 that rotate in contact with the developing roller 40 are disposed on the circumference of the developing roller 40 (see FIG. 3). Further, in the developer accommodating portion 41, developer conveying means 42 for agitating the accommodated developer and conveying it to the supply roller 43 is provided.

  As shown in FIG. 4, the developing unit 4 has the entire developing unit 4 as a drum unit 6 by a support shaft 49a around the support holes 49 provided in bearings 47 and 48 attached to both ends of the developing unit 4, respectively. Is supported so as to be able to swing.

  When the cartridge 7 is a single unit (not mounted on the printer main body), the developing unit 4 is moved by the pressure spring 64 (see FIG. 3) so that the developing roller 40 comes into contact with the photosensitive drum 1 by a rotational moment about the support shaft 49a. Always energized.

  During development, when the developer is conveyed to the supply roller 43 by the developer conveying means 42, the rotating supply roller 43 (in the direction of arrow Z in FIG. 3) is rubbed against the developing roller 40 that rotates the developer. The toner is supplied to the developing roller 40. Then, the developer is carried on the circumferential surface of the developing roller 40. The developer carried on the circumferential surface of the developing roller 40 reaches the developing blade 44 as the developing roller 40 rotates. Then, the developing blade 44 imparts a charge to the developer, and a predetermined developer thin layer is formed on the peripheral surface of the developing roller 40. The developer thin layer formed on the peripheral surface of the developing roller 40 is conveyed to a developing unit where the photosensitive drum 1 and the developing roller 40 are in contact with each other. In the developing section, the electrostatic latent image formed on the surface of the photosensitive drum 1 is developed by the developing roller 40 supplied with the DC developing bias from the power source E.

  The developer remaining on the surface of the developing roller 40 is returned to the developing container 45 as the developing roller 40 rotates. The developer is separated from the developing roller 40 by rubbing against the developer supply roller 43 and collected in the container 45.

  The developer supply roller 43 is an elastic roller made of a cored bar portion and a foamed member such as a sponge.

[How to fix the drum cleaning blade 60 to the cleaning frame 61]
Next, a method for fixing the cleaning blade 60 to the cleaning frame 61 will be described with reference to FIGS. 6, 7, and 8. 6 and 7 are views of the photosensitive drum unit 6 as viewed from the direction of arrow A in FIG. 4, and FIG. 6 is an enlarged view of a portion B in FIG. .

  The cleaning blade 60 has a base 60a (conductive member) as a metal support, and a rubber blade 60b fixed to the base by bonding or molding. That is, when the cleaning blade 60 is attached to the frame body 61, the base 60a supports the blade 60b. The base 60a is provided with a notch 60c used for positioning, a hole 60d used for positioning, and a hole 60e for a screw 59 as a fastening member for fixing the blade 60 to the cleaning frame 61. These are provided at a part of the base portion 60a in the longitudinal direction and at the other end. The notch 60c of the present embodiment has a long rectangular shape (concave shape) along the rotation axis direction of the photosensitive drum 1. As a result, errors in the direction of the photosensitive drum rotation axis can be absorbed among dimensional errors with the cleaning frame 61. On the other hand, the cleaning frame 61 is provided with a seat surface 61a and bosses 61b and 61c for positioning the blade 60 on the frame 61. The seat surface 61a is provided with a screw pilot hole 61d for fixing the blade 60. The blade 60b comes into contact with the peripheral surface of the photosensitive drum 1 to remove the deposits on the photosensitive drum 1.

  As shown in FIG. 6, the blade 60 is positioned in the Y direction on the cleaning frame 61 by aligning the side surface of the rib 61c provided on the seating surface 61a of the frame 61 with the notch 60c of the blade 60. Done. Positioning in the X direction (container longitudinal direction) is performed by aligning the boss 61b and the hole 60d. Here, the hole 60d is a long hole in the Y direction and can absorb a dimensional error of the frame 61 and the like. The Z direction is defined by the height of the seating surface 61a of the frame 61. In this way, the blade 60 is fixed to the frame body 61 with fastening members (for example, screws) 59. Thus, the amount of the tip of the rubber blade 60b of the blade 60 entering the photosensitive drum 1 is defined. Thereby, the cleaning performance can be stably obtained. 6 illustrates one end side in the photosensitive drum axial direction, the other end also corresponds to the notch corresponding to the notch 60c described above, the hole corresponding to the screw hole 60e, and the seating surface 61a. A seat surface, a boss corresponding to the boss 61c, and a hole corresponding to the prepared hole 61d are provided. Thus, the blade 60 is fixed to the frame body 61 in the same manner as described above. That is, the blade 60 is attached to the frame 61 by fixing the base 60a to the frame 61 with the screw 59 in the hole 60e.

[Attaching the charging roller to the cleaning frame]
Next, a method for attaching the charging roller 2 to the cleaning frame 61 will be described with reference to FIGS.

  FIG. 10 is an enlarged view of a portion B in FIG. 7 and shows a state in which each component is separated.

  As shown in FIG. 10, the charging roller 2 has a metal shaft 2s and a conductive rubber roller portion 2r around the metal shaft 2s. In the present embodiment, the outer diameter of the shaft 2s is about 4 mm to 6 mm, and the outer diameter of the rubber roller portion 2r is about 8 mm to 12 mm. The rubber roller portion 2r is, for example, dielectric rubber. The length of the rubber roller portion is about 225 mm to 235 mm. The rubber roller portion 2 r is in contact with the surface of the photosensitive drum 1.

  Bearings 75 and 76 (see FIG. 7) are rotatably attached to both ends of the charging roller 2. The bearing 75 is formed by molding a resin material having conductivity. The bearing 75 is provided with a boss 75 a for supporting a spring 77 for pressurizing the charging roller 2. Further, guide grooves 75b for providing engaging portions (described later) with the cleaning frame 61 are provided on the upper and lower end surfaces of the bearing 75. Similarly, the bearing 76 is provided with a boss and a guide groove for supporting the spring member (not shown).

  On the other hand, the frame body 61 is provided with guide ribs 61f as engaging portions with the receiving portions 61e of the springs 77 and the bearings 75.

  The procedure for attaching the charging roller 2 to the photosensitive drum unit 6 is as follows. First, the spring 77 is attached to the bearing 75. Then, the unit is incorporated into the spring receiving portion 61e of the frame 61. At the same time, the guide groove 75 b of the bearing 75 is engaged with the guide rib 61 f of the frame body 61. Thereafter, the charging roller 2 is fitted into the bearing 75. As a result, the charging roller 2 is attached to the frame 61. Although not shown, the side on which the bearing 76 is provided is assembled in the same procedure.

  Further, as shown in FIG. 10, an electrode plate 78 is arranged around the spring receiving portion 61e on the side where the bearing 75 is incorporated. The electrode plate 78 continues to the contact portion provided outside the frame body 61 via the inside of the frame body 61 (not shown). This contact portion is a part of a path that receives a bias from the apparatus main body 100. As a result, a charging bias is supplied to the charging roller 2 from the power source E provided in the apparatus main body 100 via the contact plate 78, the spring 77, and the bearing (conductive) 75. Here, as shown in FIG. 7, the bearing member 75 supports the shaft 2 s and simultaneously applies a bias path to the charging roller 2.

[Rubbing member of charging roller]
Next, the charging member rubbing member 70 for rubbing the peripheral surface 2 f of the charging roller 2 will be described with reference to FIGS. 7, 8 and 9. The rubbing member 70 removes deposits (for example, developer, paper dust, etc.) adhering to the peripheral surface 2 f of the charging roller 2. FIG. 8 is an enlarged view of a part of FIG.

  As shown in FIG. 9, the rubbing member 70 includes a thin plate-like elastic sheet 71 (for example, a polyimide film or a polyamide film having a thickness of 25 μm to 100 μm) and a base member (supporting part) 72. The sheet 71 is fixed to the base 72 using a double-sided tape (not shown). The sheet 71 is provided in elastic contact with the roller portion 2r along the longitudinal direction of the roller portion 2r in order to clean the deposits attached to the peripheral surface 2f of the roller portion 2r of the charging roller 2. Insulated sheet. The base 72 is fixed to the base 60a of the blade 60 using a double-sided tape (not shown).

  Here, it is important to prevent the sheet 71 from undulating in the photosensitive drum axis direction (so that there is no unevenness at the leading end) (see FIG. 9). In other words, when the sheet 71 is undulated, the sheet is struck when the charging roller 2 is attached to the bearings 75 and 76 so that the rubbing member 70 contacts the peripheral surface 2f along the longitudinal direction of the charging roller 2. A portion where 71 does not contact the charging roller 2 is generated. That is, cleaning of the charging roller 2 may be incomplete. In the present embodiment, the free length L0 of the sheet 71 is 6 mm to 10 mm, the contact length L with the charging roller 2 is 4 mm to 8 mm, and the penetration amount Δ into the charging roller 2 is 2 mm to 4 mm. Incidentally, when the undulation amount δ of the sheet 71 shown in FIG. As a method for preventing such a situation, when fixing the sheet 71 to the base member 72, a method of applying a tension to the sheet 71 by using a warp previously given to the base member 72 was adopted.

  Attachment of the rubbing member 70 in the X direction (frame body longitudinal direction) is positioned and fixed to the base portion 60a of the blade 60 so that the sheet 71 reliably covers the contact area 2t of the charging roller 2 (FIG. 11 and Fig. 12). The rubbing member 70 is not limited to being attached to the blade 60, and may be directly attached to the cleaning frame 61. Here, the contact area is an area where the roller portion 2 r is in contact with the photosensitive drum 1 in order to charge the photosensitive drum 1 in the charging roller 2 of the present embodiment.

  Further, a high voltage (1000 (V) to 1500 (V)) is supplied to the charging roller 2, so that the current flowing through the charging roller 2 does not leak to other adjacent conductive parts. Parts are assembled while maintaining a predetermined distance between the parts. However, recent image forming apparatuses are also required to be compact. Therefore, it is necessary to reduce the size of the components constituting the cartridge 7 and to efficiently arrange the components. Therefore, in this embodiment, the distance between the charging roller 2 and the conductive component (conductive member) provided adjacent to the charging roller 2 is set as small as possible. Therefore, in the present embodiment, the material of the sheet 71 as the charging member rubbing member 70 is made insulating (dielectric strength is 3 to 20 kV / mm). Further, as shown in FIGS. 11 and 12, the length of the sheet 71 elastically contacting the charging roller 2 is set to be longer than the contact area of the charging roller 2 with respect to the longitudinal direction of the charging roller 2. It is also long. The sheet 71 further extends in the longitudinal direction of the charging roller 2 from the end 2t1 of the contact area 2t (roller portion 2r) where the charging roller 2 charges the photosensitive drum 1.

  The sheet 71 is interposed between the roller portion 2r of the charging roller 2 and the head portion 59a of the screw 59 (conductive member). That is, the sheet 71 exceeds the end 2t1 in the longitudinal direction of the charging roller 2 in the contact region 2t where the charging roller 2 contacts the photosensitive drum 1 and charges the photosensitive drum 1, It is arranged between the screw 59 and the charging roller 2. The sheet 71 covers the entire area of the head 59a of the screw 59.

  That is, the sheet 71 is elastically in contact with the roller portion 2r along the longitudinal direction of the roller portion 2r. The end portion of the sheet 71 is interposed between the roller portion 2r and the head portion 59a.

  According to this embodiment, even if it is a case where a general screw is used as a fastening member, an installation space | interval can be made small. Therefore, since a general-purpose member can be used as the fastening member, cost can be reduced.

  If the sheet 71 is installed, current leakage between the charging roller 2 and the screw 59 can be prevented in addition to cleaning the surface of the charging roller 2 (roller portion 2r). Therefore, if the seat 71 is attached, it is possible to save the trouble of attaching other members to prevent current leakage. Therefore, according to this embodiment, the assembly workability of the cartridge can be improved.

  Note that the sheet 71 (charging member rubbing member 70) contacts the circumferential surface 2f of the roller portion 2r and rubs the circumferential surface 2f. Specifically, the sheet 71 is arranged along the rotation direction of the charging roller 2 (in the direction of arrow X in FIG. 8), and in the short direction of the sheet 71, the inside of the sheet 71 extends along the longitudinal direction. It is in contact with the peripheral surface 2f (so-called belly contact). Thus, it is considered that the developer adhering to the peripheral surface 2f is smoothed by the sheet 71 rubbing the peripheral surface 2f. In addition, it is considered that the developer adhering to the peripheral surface 2f is rubbed by the sheet 71 to impart triboelectric charge to the developer. Thereby, the adhesion force of the developer attached to the peripheral surface 2f to the roller portion 2r is reduced. Then, it is considered that the developer returns from the roller portion 2r to the surface of the photosensitive drum 1. Thereby, the peripheral surface 2f is cleaned by the sheet 71. Therefore, if the sheet 71 does not exist, it is possible to prevent the developer streaks from being generated in the roller portion 2r along the rotation direction of the roller portion 2r.

  In this embodiment, the length of the sheet member is set to about 320 mm with respect to the length of the roller portion 2r of about 280 mm. Thereby, one end in the longitudinal direction of the sheet 71 is disposed beyond one end in the longitudinal direction of the roller portion 2r, and the other longitudinal end of the sheet 71 is disposed beyond the other end in the longitudinal direction of the roller portion 2r. Note that the length of the sheet 71 beyond the end of the roller portion 2r is about 20 mm.

  As a result, even if the installation interval between the screw 59 and the charging roller 2 (roller portion 2r) is smaller than the previous installation interval, current leakage occurs between the screw 59 and the charging roller 2. Can be prevented. That is, it is possible to prevent the current supplied to the charging roller 2 from leaking to the screw 59. In the environment where the electrophotographic image forming apparatus is used, current leakage did not occur even though the conventional installation interval had to be 1.0 mm to 1.5 mm, even if the installation interval was 1.0 mm or less.

  That is, if the sheet 71 is not interposed, no leak occurred even in a use environment (for example, when the humidity is high) that may cause a leak.

  Therefore, the cartridge 7 can be reduced in size. Further, by making the length of the rubbing member 70 longer than the contact region 2t where the charging roller 2 is in contact with the surface of the photosensitive drum 1, the rubbing for rubbing the surface of the charging roller 2 against the rubbing member 70 is performed. In addition to the rubbing function, a function of preventing current from leaking from the charging roller 2 to the screw (conductive member) 59 can be provided.

[Second Embodiment]
Next, another embodiment will be described with reference to FIG. 13, FIG. 14 and FIG. 13 is a partial detail view of one end portion in the longitudinal direction of the charging roller 2, FIG. 14 is an explanatory diagram showing the longitudinal relationship between the charging roller 2 and the sheet 71, and FIG. It is sectional explanatory drawing which shows the relationship.

  In this embodiment, the drum cleaning member 60 is attached to the frame 61 with a double-sided tape (not shown) without using screws.

  According to the present embodiment, the sheet 71 exceeds the end 2t1 of the contact area 2t and reaches the metal shaft 2s. As a result, it is possible to prevent current from leaking between the charging roller 2 and the base (conductive member) 60a, which is a flat metal plate, as the support portion of the cleaning blade 60. This also prevents the current supplied to the charging roller 2 from leaking to the base even if the installation interval between the base 60a and the charging roller 2 is made smaller than the previous installation interval.

  In the embodiment described above, the sheet 71 does not cover the entire longitudinal direction region of the base 60a. This is because if the sheet 71 extends to the position shown in FIGS. 13 and 14, the distance between the region not covered by the sheet 71 of the base 60a and the roller portion 2r of the charging roller 2 is not caused by leakage. Because they are separated. The shaft 2s and the base 60a are separated such that the distance between them is not leaked. This is because the diameter of the shaft 2s is smaller than the diameter of the roller portion 2r.

[Other Embodiments]
According to the present invention, the process cartridge is a cartridge in which the charging member as the process means and the electrophotographic photosensitive drum are integrally formed, and the cartridge can be attached to and detached from the main body of the electrophotographic image forming apparatus. However, the present invention is not limited to this, and may further include a developing member and / or a cleaning member as process means.

  In the first embodiment described above, the sheet 71 is disposed between the screw 59 and the charging roller 2 so that the charging roller 2 passes the band of the contact area beyond both ends in the longitudinal direction of the roller. ing. This is because the screws 59 are arranged at both ends. However, the sheet 71 may be disposed beyond only one of the both end portions. For example, when the screw 59 is disposed only on one side, or when the screw 59 disposed on one side is separated from the charging roller 2 by a sufficient distance so that no leakage occurs.

  The sheet 71 is elastic and has an insulation strength of 3 to 20 kV / mm. The dielectric strength is measured by a measuring method defined in JIS standard number JIS C 2110: 1994. When the dielectric strength is smaller than 3 kV / mm, there is a risk of leakage depending on environmental conditions. Further, if the value is larger than 20 kV / mm, no leak will occur, but it will be difficult to obtain on the market. On the other hand, since the sheet of a commercially available material can be used if it is 20 kV / mm or less, the cost is not increased.

  Here, in the first embodiment described above, the conductive member is a metal screw 59 for fixing the drum cleaning member 60 to the cleaning frame 60. In the second embodiment, the conductive member is a base 60a as a support portion, which is a flat metal plate that supports the blade 60b of the drum cleaning member. However, the conductive member is not limited to the above-described component, and a component that is close to the charging member (shaft, roller portion) can be appropriately selected.

  In the above-described embodiment, the roller-shaped charging roller 2 has been described as an example of the charging member. However, the charging roller 2 is in contact with the electrophotographic photosensitive drum and supplied with the charging bias received from the apparatus main body. Any member that charges the photosensitive drum may not be a roller. For example, an endless belt (charging belt) that can be rotated in contact with the photosensitive drum is provided, and the configuration in which the photosensitive drum is charged by the charging belt can be applied in the same manner as the charging roller. it can.

  Conventionally, when a charging bias of about 1000 V is supplied, the installation interval between the charging roller 2 and the conductive member (component) is defined as 1.0 mm or more. This is because current leakage may occur when the two are brought closer than 1.0 mm in the predicted use environment of the electrophotographic image forming apparatus. In addition, as a use environment, an environment with high humidity is mentioned.

  However, according to the above-described embodiment, even if the installation interval between the charging roller 2 and the conductive member is smaller than the conventional installation interval of 0.7 mm, the possibility of current leakage is eliminated.

  That is, the possibility of current leakage is eliminated in any expected use environment of the electrophotographic image forming apparatus. For example, according to the above-described embodiment, even when the above-described charging bias is supplied to the charging roller 2, both can be brought close to about 0.7 mm.

Sectional drawing which shows the whole structure of the full-color image forming apparatus to which one Embodiment of this invention is applied. Sectional drawing which shows the whole structure of the full-color image forming apparatus to which one Embodiment of this invention is applied. Sectional drawing which shows the whole structure of the process cartridge to which one Embodiment of this invention is applied. The perspective view which shows the state which decomposed | disassembled the process cartridge Perspective view showing process cartridge 1 is an exploded perspective view of a process cartridge to which an embodiment of the present invention is applied. 1 is an exploded perspective view of a process cartridge to which an embodiment of the present invention is applied. 1 is a partial sectional view of a process cartridge to which an embodiment of the present invention is applied. 1 is a partial perspective view of a process cartridge to which an embodiment of the present invention is applied. The fragmentary perspective view which shows embodiment of the process cartridge to which one Embodiment of this invention is applied FIG. 3 is a partial detail view of a process cartridge to which an embodiment of the present invention is applied. 1 is an overall view of a process cartridge to which an embodiment of the present invention is applied. The partial detail figure which shows embodiment of the process cartridge to which one Embodiment of this invention is applied 1 is an overall view of a process cartridge to which an embodiment of the present invention is applied. 1 is a partial sectional view of a process cartridge to which an embodiment of the present invention is applied.

Explanation of symbols

E ... Main body power supply 1 (1a, 1b, 1c, 1d) ... Electrophotographic photosensitive drum 2 (2a, 2b, 2c, 2d) ... Charging roller (charging member)
2f ... peripheral surface of charging roller (roller part) 2r ... roller part 2s ... metal shaft 2t ... contact area 2t1 ... end 3 ... scanner unit 4 ... developing unit, developing device 6 ... photosensitive drum unit 7 (7a, 7b, 7c) 7d) Process cartridge
40… Development roller
41… Developer storage
42… Conveying means
43… Developer supply roller
44… Developer blade
45… Developing container
47, 48… Development bearing
49… support hole
49a… support shaft
59 ... Screw (conductive member)
59a ... head
60… Drum cleaning blade
60a ... base
60b ... Blade
60c ... Notch
60d hole
60e… hole
61… Cleaning frame
61a ... Seat
61b, 61c ... Boss
61d ... Screw pilot hole
61e… receiving part
61f… Guide rib
62… Developer feed mechanism
63… Removal developer chamber
64… Pressure spring
70… charging member rubbing member
71… Sheet (Charging member rubbing member)
72… Base member (conductive member)
75, 76… Bearing
75a ... Boss
75b… Guide groove
77… Spring
78… Electrode plate
80… Wearing part
100 ... Electrophotographic image forming apparatus main body

Claims (8)

In a process cartridge that can be attached to and detached from the electrophotographic image forming apparatus main body,
An electrophotographic photosensitive drum;
It is provided in contact with the electrophotographic photosensitive drum, and when the process cartridge is mounted on the electrophotographic image forming apparatus main body, a charging bias received from the electrophotographic image forming apparatus main body is supplied, A charging member for charging the electrophotographic photosensitive drum;
An insulating charging member rubbing member provided in contact with the charging member along the longitudinal direction of the charging member;
Have
In order to prevent current from leaking from the charging member to the conductive member when the charging bias is supplied to the charging member, the charging member charges the electrophotographic photosensitive drum. The charging member rubbing member is disposed between the conductive member and the charging member beyond the end portion in the longitudinal direction of the charging member in the contact area in contact with the electrophotographic photosensitive drum. A process cartridge characterized by comprising: Further, the process cartridge has a drum cleaning member for removing deposits attached to the electrophotographic photosensitive drum, and the conductive member is made of a metal for fixing the drum cleaning member to the cartridge frame. The process cartridge according to claim 1, wherein the process cartridge is a screw. Further, the process cartridge has a drum cleaning member for removing deposits attached to the electrophotographic photosensitive drum, and the conductive member is a metal plate that supports a blade of the drum cleaning member. The process cartridge according to claim 1, wherein the drum cleaning member is attached to the cartridge frame by fixing the metal plate to the cartridge frame. 2. The charging member rubbing member, wherein the charging member is disposed between the conductive member and the charging member beyond both end portions in the longitudinal direction of the contact region. The process cartridge according to claim 3. The process cartridge according to claim 1, wherein the charging member rubbing member covers the entire region of the conductive member in the longitudinal direction. 6. The process cartridge according to claim 1, wherein the charging member rubbing member has a dielectric strength of 3 to 20 kV / mm. The charging member rubbing member is an elastic sheet, and is in elastic contact with the roller portion along the longitudinal direction of the roller portion of the charging roller, and the end of the sheet is the roller portion. 7. A process cartridge according to claim 1, wherein the process cartridge is interposed between the head of the screw and the conductive member. In an electrophotographic image forming apparatus for forming an image on a recording medium,
(1) Main unit power supply,
(2) a mounting part;
(3) an electrophotographic photosensitive drum;
It is provided in contact with the electrophotographic photosensitive drum, and when the process cartridge is mounted on the electrophotographic image forming apparatus main body, a charging bias received from the electrophotographic image forming apparatus main body is supplied, A charging member for charging the electrophotographic photosensitive drum;
An insulating charging member rubbing member provided in contact with the charging member along the longitudinal direction of the charging member;
Have
In order to prevent current from leaking from the charging member to the conductive member when the charging bias is supplied to the charging member, the charging member charges the electrophotographic photosensitive drum. The charging member rubbing member is disposed between the conductive member and the charging member beyond the end portion in the longitudinal direction of the charging member in the contact area in contact with the electrophotographic photosensitive drum. A process cartridge that is detachably mounted on the mounting portion;
An electrophotographic image forming apparatus comprising:

Images